Gas spring curve control in an adjustable-volume gas-pressurized device

ABSTRACT

A gas spring curve control valve for a adjustable-volume gas-pressurized device is described. The valve allows for selection from among at least four spring curves and can be packaged in small spaces/devices. In an exemplary embodiment of the invention, a rotary cam having grooves and lobes that interact with spring loaded ball bearings and an external adjuster knob are used to easily change the gas spring curve “on-the-fly” and with minimal user effort.

RELATED PATENT APPLICATIONS

This application is related to our U.S. patent applications:

a) Ser. No. 10/237,333, filed Sep. 5, 2005, published as US Pub.2003/0234144 (the “'144 application”) on Dec. 25, 2003, and entitled “Onthe Fly Adjustable Gas Spring”; and

b) Ser. No. 11/372,707, filed Mar. 10, 2006, and entitled “Gas Springand Travel Control For Same and Method.”

All patents and patent applications referred to herein are incorporatedby reference into this patent application.

FIELD OF THE INVENTION

The current invention is directed to improvements useful in gas-springdevices and other variable-volume gas-pressurized devices that operateaccording to the gas spring characteristics (i.e., pressure v. chambervolume) they produce during operation. For purposes of this patentapplication, all such devices are collectively referred to herein asadjustable-volume gas-pressurized devices. The current invention isespecially directed to providing such devices with the ability to havetheir gas spring curves easily changed by the rider on-the-fly. Thecurrent invention is especially suitable for use with, for example:

(a) gas springs used in two-wheeled vehicles, such as: bicycle shockabsorbers (e.g. our '144 application), or bicycle suspension forks (e.g.our U.S. Pat. No. 6,592,136); and

(b) shock absorbers having a chamber containing a pressurized gas forcontrolling the pressure on a hydraulic fluid and/or controlling theeffect or extent of a pressure-sensitive damping effect, as exemplifiedby our WO2006/054994.

BACKGROUND OF THE INVENTION Introduction

Just like any other type of spring, gas springs have spring curves thatdefine the force v. deflection characteristic for the spring. In thefield of gas springs and especially those used in vehicles, it is wellknown that it is often advantageous for the gas spring curve of the gasspring to be able to be changed. Accordingly, our '144 applicationextensively describes the advantages of a gas spring performingaccording to a gas spring curve selected—by the rider—from a number ofdifferent spring curves (i.e., “softer” and “stiffer”). The need for agas spring to perform according to a gas spring curve selected—by therider—from a number of different spring curves (i.e., “softer” and“stiffer”) is also generally discussed in the prior art, such as in USPub 2005/0116399.

It is highly desirable that the gas spring curve of the gas springshould be able to be easily changed by the rider on-the-fly. Typically,for example, in the bicycle arts, a successful “on-the-fly” adjustmentshould: (1) be able to made without tools; (2) require small controllermanipulations (e.g. short angular knob rotations); (3) require lowforces/torques to manipulate the controller; and (4) be capable of beingmade very quickly (for example, in one or two seconds) and without therider having to stop or dismount.

Discussion of Prior Art

The prior art includes a number of adjustable-volume gas-pressurizeddevices that, while capable of being adjusted to provide various gasspring curves, are not capable of, or conducive to, easy on-the-flyadjustment.

For example, a number of adjustable gas spring designs require rotatingan adjustment cap against a significant amount of torque for a full 360°or more, to change the gas chamber volume. As examples, see, e.g. RisseRacing (“Remote Adjustable Gas Chamber”); Showa (U.S. Pat. No. 5,346,236and Showa Advertisement, Mountain Bike 22-23 (June 1994)); Berthold(U.S. Pat. No. 5,957,252); Rockshox (U.S. Pat. No. 6,095,541); and SRAM(US Pub. 2005/0116399). (For completeness, we note here that therotation adjustment described in SRAM '399, besides changing gas chambervolume, also changes total fork travel.)

Additionally, in the DHX 5® shock absorber made by FOX FACTORY, INC.,the assignee of the current invention, adjusting the independentbottom-out resistance, which operates according to a gas spring curve asgenerally described in paragraphs [0079]-[0080] of our WO2006/054994,requires a significant amount of torque to rotate the control knob.

It is also known to those skilled in the art that by changing the volumeof the oil in the damper, the air spring response can be adjusted. Seee.g. Showa Advertisement (referred to above) (referring to common priorart practice: “Have you ever changed the oil volume in your suspension?Does it take a great deal of your time?”); Rick Sieman, “Do It YourselfTech—Dial in Your Own Forks” (www.off-road.com/dirtbike/tech/forks/);“How to Improve the Ride and Suspension Performance of CruiserMotorcycles”(www.motorcyclecruiser.com/tech/improve_ride_suspension_performance/);“Suspension Tuning Guide—Learning the Lingo”(www.sportrider.com/tech/146_(—)0006_lingo). With this method,depressurization of the gas spring is required before the oil may beadded or removed and then re-pressurization of the gas spring isrequired before use.

Other methods that require depressurization and re-pressurization of thegas spring during the course of making the spring curve adjustment are:(a) rotating internal parts using an Allen-wrench (e.g. 1998 RockshoxSID); (b) adding a volume spacer (e.g. 1999-2000 Rockshox SID); and (c)re-locating an internal volume plate (Cane Creek AD-10 and AD-12 rearshocks and U.S. Pat. No. 5,775,677).

When a rider has to exert this much effort and labor to make springcurve adjustments, the gas spring curve adjustment cannot be consideredan on-the-fly adjustment—no less a practical on-the-fly adjustment.

As described in our '144 application, spring curves in a gas spring canbe changed by altering the initial gas chamber volume. Increasing ordecreasing the initial gas chamber volume softens or stiffens,respectively, the gas spring curve. The '144 application describes thetheory and formulas underlying how varying gas chamber volumes effectsspring curves. Note also that gas springs are sometimes referred to airsprings because the gas they use is often air.

Selectively placing main and auxiliary gas chambers in fluidcommunication with each other to alter the total gas volume subject tocompression and therefore the gas spring curve of the gas spring hasbeen widely used in various constructions in automobiles (U.S. Pat. No.1,094,567; U.S. Pat. No. 4,206,934; U.S. Pat. No. 4,534,580; U.S. Pat.No. 4,592,540; U.S. Pat. No. 4,598,929; U.S. Pat. No. 4,613,116; U.S.Pat. No. 4,616,811; U.S. Pat. No. 4,635,906; U.S. Pat. No. 4,651,977;U.S. Pat. No. 4,653,735; U.S. Pat. No. 4,659,070; U.S. Pat. No.4,697,796; U.S. Pat. No. 4,673,171; U.S. Pat. No. 4,735,401; U.S. Pat.No. 4,746,106; U.S. Pat. No. 4,768,758; U.S. Pat. No. 4,773,635; U.S.Pat. No. 5,915,674; U.S. Pat. No. 6,883,810; U.S. Pat. No. 6,698,730;U.S. Pat. No. 6,708,803; JP61-1135808; DE 10236621; DE 3233160; and DE4018712). Additionally, in an automotive application, JP61-1135808teaches that a main chamber may be used in combination with two remotegas chambers to provide for three different spring curves.

However, the bulky, motor driven, electronically controlled,multi-component, and external (to the gas spring housing) devicesdisclosed in much of the previously mentioned automotive prior art andused to achieve this functionality are not conducive to un-powereddevices, compact and lightweight packaging, and/or incorporation intosmaller adjustable-volume gas-pressurized devices, such as used inbicycle or other two-wheeled vehicle suspensions.

Indeed, as compared to the automotive solutions described above, therehas been much less success in finding innovative ways to providetwo-wheeled vehicle riders with the ability to easily and quickly changethe gas spring curve of adjustable-volume gas-pressurized deviceson-the-fly. Currently used methods remain labor or effort intensive andnot are conducive to on-the-fly adjustment. As mentioned above, the mostwidely used current two-wheel vehicle solutions involve:

1. Rotating an external knob or nut against significant torque, e.g.Showa; Risse Racing; Rockshox ('541); SRAM ('399); Bethold (U.S. Pat.No. 5,957,252); FOX DHX (WO06/054994);

2. Adding or removing oil after depressurization of the gas spring, e.g.various sources mentioned above;

3. Rotating an internal part to increase or decrease the gas chambersize after depressurization of the gas spring and requiring use of anAllen wrench, e.g. 1998 RockShox SID;

4. Adding a “volume spacer” to increase or decrease the gas chamber sizeafter depressurization of the gas spring, e.g., 1999-2000 RockShox SID;and

5. Re-locating an internal ‘Volume Plate’ to increase or decrease thegas chamber size after depressurization of the gas spring, e.g., CreekAD-10 and AD-12 rear shocks (See U.S. Pat. No. 5,775,677).

Accordingly, the current invention, as will be described below, providesvery practical and simple ways for two-wheeled vehicle riders to havethe ability to easily and quickly change the gas spring curve ofadjustable-volume gas-pressurized devices on-the-fly.

Damping Forces v. Spring Forces

Recognizing the difference between spring curves and so-called gasdamping is important to an appreciation of the current inventionrelative to the prior art. Gas damping has been defined in at least onesource as a damping force that results from gas being forced through“proper” (i.e., smaller) orifices. See Jack Gieck, Riding on Air: AHistory of Air Suspension 222 (1999). See also U.S. Pat. No. 5,775,677(discussing and suggesting using gas as a damping medium). However,Gieck also writes that the idea that a gas flowing through an orificecan be used to create a damping force has generally been a blind alleyand that the perceived damping effect can be explained with the theorythat the smaller orifices actually temporarily isolate/separate the gasvolumes. See Gieck at 222. While on a purely theoretical level, theremay be a question as to whether there really is such a thing as true“gas damping”, some in the industry do make reference to and apply sucha phenomena. See Rockshox 1998 SID User's Manual (“Air Damping OrificeAdjuster”). Accordingly, if we accept that the term “gas damping”loosely defines a result rather than how that result is achieved, thecurrent invention has widespread applicability, for example inapplications:

(a) where large gas-flow orifices that do not introduce a so-called gasdamping effect are used, and the gas flows through the valve orificesand from one gas chamber to another with little or no resistance orthrottling and virtually instantaneously; or

(b) where smaller orifices that may sometimes be described asintroducing a so-called gas damping effect may be preferred.

For purposes of the invention, “instantaneous” is considered on theorder of milliseconds. For a typical mountain bike air fork operatingunder normal conditions, e.g., gas chamber volumes, pressures, andtemperatures, a gas flow port on the order of about 0.050″ diameter orlarger will achieve a virtually instantaneous flow. A flow of thisnature probably would not be considered to introduce a gas dampingeffect.

On the other hand, under the same conventional conditions, a gas flowport having a diameter of approximately 0.005″, would not result in avirtually instantaneous flow. Rather, it would take, for example,approximately 0.8 seconds for the pressure between the two gas chambersto equalize when such a small flow port is used. For purposes of theinvention, a flow that takes “on the order of” 0.8 seconds can beconsidered to be restricted, throttled and not virtually instantaneous.A flow of this nature probably would be considered to add a gas dampingeffect.

Therefore, as used herein when describing the various exemplaryembodiments of the invention, “fluid communication” means that gas mayflow from one gas chamber to another, even if that gas flow is beingthrottled. “Unrestricted fluid communication” as used in thisapplication means gas flows from one gas chamber to another with littleor no resistance or throttling and virtually instantaneously.

Both restricted and unrestricted fluid communication are within thescope of the invention and which is used depends on the specificperformance characteristics desired by the user.

Gas Spring Curves, Travel Modes and Compression Ratios

So far, reference has only been made to different gas spring curves.However, as described in the '144 application, the stiffness (gas springcurve) of a gas spring may be associated with “travel modes” andcompression ratios. For conciseness and clarity, the extensivebackground and exemplary calculations provided in the '144 applicationon these concepts will only be summarized here.

Travel modes, e.g., short travel modes and long travel modes, aregenerally defined by how far a spring compresses when subjected to agiven force. Thus, as described in the '144 application, for a givenforce, when a gas spring is in short travel mode it compresses less thanit would if the gas spring is in long travel mode.

Compression ratio is defined in our '144 application as initial volumeof a gas spring (i.e., at full expansion) divided by the final volume ofthe gas spring (i.e., at full compression). For a given initialpressure, higher compression ratios produce higher pressures at anygiven travel distance, thus requiring larger forces for compression.Reference should be made to the '144 application for exemplarycompression ratio and compressive force calculations.

In the '144 application, the long travel mode is operative and thecompression ratio is lowest when the two gas chambers are in fluidcommunication and the short travel mode is operative and the compressionratio is highest when the two gas chambers are not in fluidcommunication.

As will be described below, this terminology is applicable to thecurrent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a suspension fork including a gas spring having a gasspring curve control valve according to a first exemplary embodiment ofthe invention. The suspension fork may be similar to the suspension forkshown in, for example, our U.S. Pat. No. 6,592,136.

FIGS. 1B and 1C depict portions of shock absorbers including a chambercontaining a pressured-gas and having a gas spring curve control valveaccording to a first exemplary embodiment of the invention. Inparticular:

FIG. 1B depicts a remote reservoir for use with a shock absorber havinga gas spring curve control valve according to a first exemplaryembodiment of the invention.

FIG. 1C depicts a portion of a monotube De Carbon-type shock absorberincluding a gas spring curve control valve according to a firstexemplary embodiment of the invention

FIG. 2A depicts a perspective exploded view of a gas spring curvecontrol valve according to a first exemplary embodiment of theinvention.

FIGS. 2B-D depict perspective exploded views of different sub-assembliesof a gas spring curve control valve according to a first exemplaryembodiment of the invention

FIG. 3 depicts a cross-section view of generic adjustable-volumegas-pressurized device including a gas spring curve control valveaccording to a first exemplary embodiment of the invention.

FIG. 4A is a view below line 4A-4A of FIG. 3.

FIG. 4B is a view above line 4B-4B of FIG. 3.

FIG. 4C is a view along line 4C-4C of FIG. 3.

FIG. 5 depicts a highly schematic representation of a differentpositioning of the gas spring curve control valve relative to a genericadjustable-volume gas-pressurized device.

FIGS. 6A-D depict axial cross-section of the gas spring curve controlvalve according to the first embodiment of the invention in each of itsavailable settings.

FIGS. 7A-D are views along lines 7A-7D of FIGS. 6A-D, respectively.

FIGS. 8A-8D are views along lines 8A-D of FIGS. 6A-D, respectively.

FIGS. 9A-9D are views along lines 9A-D of FIGS. 6A-D, respectively.

FIG. 10A, 10B depict the pressurization of a generic adjustable-volumegas-pressurized device using the gas spring curve control valveaccording to the first embodiment of the invention.

FIG. 11 is a high-level block diagram schematically depictingalternative methods for adjusting the first embodiment of the gas springcurve control valve.

FIG. 12 depicts a gas spring curve control valve according to analternative embodiment of the invention.

FIGS. 13A-F depict the ball valves of the gas spring curve control valveof FIG. 12 in each of its available positions.

FIG. 14 depicts a portion of a gas spring curve control valve accordingto another alternative embodiment of the invention.

FIG. 15A depicts a portion of a gas spring curve control valve accordingto another alternative embodiment of the invention.

FIG. 15B is a view along line 15B-15B of FIG. 15A.

FIGS. 16A-16D depict axial cross-section of the gas spring curve controlvalve according to FIG. 15A in each of its available settings.

FIGS. 17A-17D are views along lines 17A-D of FIGS. 16A-16D,respectively.

For simplicity and clarity, reference numerals have been provided on thevarious Figures only when such reference numerals are actually discussedin the text associated with the Figure. Additionally, similar structuresin the various Figures have been given the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION Introduction

As previously mentioned, the concepts underlying the gas spring curvecontrol valve 20 according to the various exemplary embodiments of theinvention have widespread applicability. However, the concepts areespecially applicable to bicycle suspension forks (e.g. FIG. 1A) orbicycle shock absorbers having gas springs (the '144 application) orhydraulic shock absorbers 2 having a chamber containing pressurized gasfor pressurizing a hydraulic fluid and, in which, the pressurized gasand hydraulic fluid may be separated by an internal floating piston 3(FIGS. 1B, 1C) or some other type of barrier such as a bladder ordiaphragm (not shown). Due to the fact that the gas spring curve controlvalve 20 according to the invention has such wide-spread applicabilityand may be easily retrofitted into many existing devices, the specificdetails of the various adjustable-volume gas-pressurized devices towhich the invention may be applied are only shown schematically herein.Reference should be made to any of the various patents and patentapplications cited herein for extensive background that will not berepeated herein to maintain clarity and conciseness.

Basic Structure of an Exemplary Embodiment

Thus, FIG. 3 depicts an overall view of an exemplary embodiment of a gasspring curve control valve 20 associated with a generic self-containedadjustable-volume gas-pressurized device 1 (e.g., shock absorber gasspring, fork gas spring, shock absorber reservoir, etc.) having ageneric housing 10.

FIGS. 2A-D depict gas spring curve control valve 20 alone (FIG. 2A) andas various sub-assemblies (FIG. 2B-D). Housing 10 (FIG. 3) may comprise,for example, a reservoir cylinder, an upper portion of an upper leg of asuspension fork, a portion of a shock absorber, or a portion of anyother gas-pressurized device, e.g., door arrestor, chair riser, etc.Housing 10 will typically be cylindrical and tubular and may be alignedin any orientation (e.g. horizontal, oblique, or vertical) and mountedto some structure with which it is associated in any conventional manner(e.g. eyelets, trunions, brackets, etc.). Housing 10 has an inner wall10 a and will have at least one open end 11. Furthermore, housing 10will typically contain most of the working parts associated with theadjustable-volume gas-pressurized device 1, for example, whenapplicable, any of internal floating piston 3, piston 12, a portion ofpiston shaft 13, main gas chamber C, and the auxiliary gas chambers,e.g., A1, A2, which may be in-line.

Gas spring curve control valve 20 includes body portion 25 that may bescrewed into open end 11 of housing 10 using threads 21 (FIG. 2A) tosecure gas spring curve control valve 20 to housing 10 against theinternal gas pressure of main gas chamber C. Body portion 25 of gasspring curve control valve 20 may include a first end 25 a and a secondend 25 b connected to each other by hollow tubular portion 25′. Thesethree elements may be formed from either a unitary or integralconstruction. Seals 26 prevent gas contained within the various gaschambers of housing 10 from leaking between chambers or out of housing10 entirely. As described below, gas spring curve control valve 20 has aplurality of discrete settings for controlling whether the main chamberC operates alone, or in fluid communication with at least one, butpreferably two or more, auxiliary gas chamber during a compressionstroke. The operative setting is based on the user's selection fromamong the various available settings.

As shown in FIG. 3 and FIG. 4A, first end 25 a of body portion 25 maydefine one end of main gas chamber C. In the exemplary embodiment ofFIG. 3, the body portion 25 of gas spring curve control valve 20′ isgenerally coaxial with piston shaft 13. In the alternative exemplaryembodiment of FIG. 5, which highly schematically depicts a genericadjustable-volume gas-pressurized device, gas spring curve control valve20′ is positioned within a side valve housing 10′ intermediate the endsof housing 10 of adjustable-volume gas-pressurized device 1 and havingan axis X-X that may be perpendicular to piston shaft 13.

Returning to FIGS. 2A-D, 3, 4A, body portion 25 has at least onepartition 35 positioned between ends 25 a, 25 b for dividing the volumebetween the ends 25 a, 25 b into two separate volumes, i.e., firstauxiliary gas chamber A1, and second auxiliary gas chamber A2.Accordingly, portions of body portion 25 and the inner wall 10 a ofhousing 10 at least partially define the first and second auxiliary gaschambers A1, A2. As described with respect to FIGS. 12, 13 below, anynumber of additional partitions 35 may be used to define additionalauxiliary gas chambers. As one skilled in the art would recognize, theposition of partition 35 relative to the first end 25 a and the secondend 25 b determines the absolute and relative sizes of the auxiliary gaschambers with respect to each other and main gas chamber C and thereforethe compression ratios/spring curves of the spring.

Valve Structure of an Exemplary Embodiment

Focusing now on FIGS. 2B and 4A, body portion 25 has a first gas flowport 40 for allowing the main gas chamber C and the first auxiliary gaschamber A1 to be placed in fluid communication. Body portion 25 has asecond gas flow port 45 for allowing the main gas chamber C and thesecond auxiliary gas chamber A2 to be placed in fluid communication. Asdescribed above, when virtually instantaneous gas flow is desiredthrough gas flow ports 40 and 45, the gas flow ports 40, 45 should besized to provide virtually no restriction or throttling of gas flow. Asan example, a flow port diameter of approximately 0.050″ or larger couldbe used in an application of the current invention to a typical bicycleair spring front fork. When a slower gas flow is desired, the gas flowports will be sized much smaller.

Gas spring curve control valve 20 may include ball valves 50 a, 50 b forcontrolling fluid communication between the main gas chamber C and theauxiliary gas chambers A1, A2, respectively, by selectively preventinggas flow from the main chamber C into first auxiliary chamber A1 orsecond auxiliary chamber A2 through the first and second gas flow ports40, 45, when ball valves 50 a, 50 b are in their closed positions, or byselectively allowing the gas flow when ball valves 50 a, 50 b are intheir open positions. In FIGS. 3, 4A, ball valve 50 a is in its openposition and ball valve 50 b is in its closed position. As will bedescribed below with respect to FIGS. 15-17, gas spring curve controlvalve 20 may include valve elements other than ball valves; for example,a rotary disc valve.

As shown in FIG. 2B, 4A, ball valves 50 a, 50 b may comprise check balls51 a, 51 b that are loaded by springs 52 a, 52 b against seals 53 a, 53b to normally bias the ball valves 50 a, 50 b closed to prevent fluidcommunication from the main gas chamber C to the first and secondauxiliary gas chambers A1, A2. Cap 54 retains springs 52 undercompression. Cap 54 has large unobstructed gas flow openings 55. Asdescribed in our '144 application, the small bias forces produced bysprings 52 a, 52 b, prevent unintended entrapment of excess gas andpressure in the auxiliary gas chambers A1, A2.

A rotor 60 (see also FIG. 2A, 2C, 2D) is fixed to cam 70, which isassociated with the first and second ball valves 50 a. 50 b such thatrotation of the rotor 60 selectively opens both, one, or neither of thefirst and second ball valves 50 a, 50 b. Rotor 60 may comprise rotorhead 61 (FIG. 2D, 4B) and rotor tube 62 (FIG. 2D, 4A) and may beconstructed either as an integral or unitary structure. Rotor head 61may include rotor stop flats 61 a (FIG. 2D) that interact with body stopflats 25 c (FIG. 2C) to limit the available rotation of rotor 60, asfurther described below.

Hollow tubular portion 25′ of body portion 25 may receive rotor tube 62.Seal 63 (FIG. 3, 4B) prevents gas leakage from adjustable-volumegas-pressurized device 1 from the gas spring control valve 20. Rotortube 62 of rotor 60 defines a pressurization flow path 64 having an exitport 65, both of whose functions are described below, relative topressurization of adjustable-volume gas-pressurized device 1. Adjustmentknob 67 is associated with rotor 60 in any such manner, for example,using a screw 68, that allows rotation of adjustment knob 67 to controlwhich, if any, of ball valves 50 a, 50 b are open. A plurality of ballbearings 69 a rolling within race 69 b (FIG. 2C) and spaced apart byelements 69 c provide for a robust rotation platform that also has avery smooth feel to the user. Lever 67′ gives a visual indication of thesetting of adjustment knob 67. Adjustment knob 67 is positioned externalto housing 10 and within the reach of the rider while in the ridingposition so that adjustment knob 67 may be quickly and simply directlymanipulated by a user in an on-the-fly manner.

As shown in FIG. 4A, cam 70 is associated with rotor 60, such as byattachment to the lower end of rotor tube 62 using a fastener, such as ascrew 71. Rotor slot 60 a (FIG. 2A, 2C, 2D) interlocks with cam tab 70 a(FIG. 2A, 2B) to assure there is no relative movement between rotor 60and cam 70. Therefore, rotating rotor 60 also rotates cam 70. As shownin FIG. 4C, cam 70 has a number of lobes 72 and grooves 73 forselectively deflecting check balls 51 as rotor 60 and cam 70 arerotated. In FIG. 4C, check ball 51 a is deflected and check ball 51 b isnot. Deflection of a check ball 51 a, 51 b results in the opening of theball valve 50 a, 50 b associated with that check ball 51 a, 51 b. Thus,for example, in FIG. 4C, the deflection of check ball 51 a away from itsassociated seal 53 a creates a space 56 through which gas may into thefirst gas flow port 40 and from main gas chamber C to first auxiliarychamber A1. Lobes 72 and grooves 73 may be sized and angularly arrangedaround cam 70 to provide desired combinations of chambers in fluidcommunication.

Referring now to FIGS. 6-9 (note that for clarity, housing 10 has beenomitted from FIGS. 6A-6D), the operation and function of an exemplaryembodiment of the invention having four discrete settings will bedescribed:

1) As seen in FIGS. 6A-9A, when lever 67′ is in a first setting, the cam70 has deflected both of check balls 51 a, 51 b to their open positions.In this setting, two-way fluid communication between main gas chamber Cand first and second auxiliary gas chambers A1, A2 is enabled;

2) As seen in FIGS. 6B-9B, when lever 67′ is in a second setting, thecam 70 only deflects one of the check balls 51 to the open position (thecheck ball on the right side, as shown in FIGS. 6B and 9B). In thissetting, as shown, there is two-way fluid communication between main gaschamber C and second auxiliary gas chamber A2, but no fluidcommunication from main gas chamber C to first auxiliary gas chamber A1;

3) As shown in FIGS. 6C-9C, when lever 67′ is a third setting, the cam70 only deflects the check ball on the left side to the open positions,as shown in FIGS. 6C and 9C. In this setting, as shown, there is two-wayfluid communication from main gas chamber C to first auxiliary gaschamber A1, but no fluid communication from main gas chamber C to secondauxiliary gas chamber A2; and

4) As seen in FIGS. 6D-9D, when lever 67′ is in a fourth setting, thecam 70 does not engage either check ball 51 a, 51 b, and both checkballs 51 a, 51 b are urged into closed positions by their respectivesprings 52. In this setting, as shown, any fluid communication betweenmain gas chamber C and first and second auxiliary gas chambers A1, A2 isprevented.

As we discussed in our '144 application, it is preferable for adjustmentknobs to be capable of manipulation quickly and simply by a user, manytimes during a ride. Therefore, in the '144 application, the adjustmentknob needed only ¼ rotation to switch between the softer and stifferspring curves available with that design. With the current invention,quick and simple manipulation of adjustment knob 67 by a user may beachieved by designing cam 70 such that the complete range of settingsfor gas spring curve control valve 20 may easily be achieved in lessthan ½ turn of adjustment knob 67. For example, in the preferredembodiment shown in FIGS. 6-9, the individual valve settings areapproximately 45° apart, resulting in a total angular sweep of 135°covering all 4 discrete settings. Smaller angular increments (say 30°for giving a total sweep of 90°, for example), could easily be providedif desired. As described above, the end points for the rotation ofadjustment knob 67 and rotor 60 relative to body portion 25 are limitedby stop flats 61 a and 25 c (compare FIG. 8A with FIG. 8D).

These different gas spring curve control valve settings may besummarized as set forth in the table below.

TABLE ONE Exem- Effective Exem- Valve plary Total plary 20 Angular BallBall Volume Compres- Set- Position valve valve Occupied sion ting ofKnob 50a 50b By Gas Ratio FIG 1 0° Open Open C + A1 + A2 3.9 6A–9A 2 45°Closed Open C + A2 4.6 6B–9B 3 90° Open Closed C + A1 5.3 6C–9C 4 135°Closed Closed C 7.0 6D–9D

Pressurization of the Gas Spring

As shown in FIG. 4B, pressurization assembly 80, including aconventional Schrader valve, is placed in fluid communication withpressurization flow path 64. Pressurization assembly 80 may be protectedby a removable cap 81. Pressurization of adjustable-volumegas-pressurized device 1 is shown in FIGS. 10A, 10B. As shown in FIG.10A, the gas spring control valve 20 is first set to its setting whereboth ball valves 50 a, 50 b are open. Then, gas from a pressure sourceP, such as a conventional hand-operated pump is injected throughpressurization assembly 80 and flows through pressurization flow path 64and exit port 65 into pressurization channel 82 of body portion 25.Pressurized gas within pressurization channel 82 flows through theun-sealed spaces 56 between check balls 51 and cam 70 (FIG. 10B) andinto the main gas chamber C. Additionally, because ball valves 50 a and50 b are open, the incoming pressurized gas also fills auxiliarychambers A1, A2 and a constant gas pressure is communicated throughoutall the various chambers of the gas spring.

Basic Method of Use

As described in our '144 application, the gas spring curve of a gasspring is determined by the volume of the gas subject to compression.The larger the volume, the softer the spring and the smaller the volumethe stiffer the spring. We now apply this principle to the currentinvention.

When the lowest spring curve is desired for adjustable-volumegas-pressurized device 1, adjustment knob 67 is set by the user to thesetting where both ball valves 50 a, 50 b are open (FIG. 6A-9A). Openball valves 50 a, 50 b place main gas chamber C in fluid communicationboth first A1 and second auxiliary gas chamber A2 and the three gaschambers act as a single volume. Thus, because during movement of thepiston 3 or 12 towards gas spring control valve 20, the total volume ofgas contained within main gas chamber C and both auxiliary gas chambersA1, A2 are subject to compression, the lowest spring curve results.

When a stiffer spring curve is desired for adjustable-volumegas-pressurized device 1, adjustment knob 67 is set by the user to thesetting where only ball valve 50 b is open (FIG. 6B-9B). Open ball valve50 b places main gas chamber C and second auxiliary gas chamber A2 influid communication and the two gas chambers act as a single volume. Inthe exemplary embodiment of the invention, second auxiliary gas chamberA2 has a larger volume than first auxiliary gas chamber A1. Thus,because during movement of the piston 3 or 12 towards gas spring controlvalve 20, only the volume of gas contained within main chamber C andsecond auxiliary chamber A2 are subject to compression, a stiffer springcurve results.

When an even more stiff spring curve is desired for adjustable-volumegas-pressurized device 1, adjustment knob 67 is set by the user to thesetting where only ball valve 50 a is open (FIG. 6C-9C). Open ball valve50 a places main gas chamber C and first auxiliary gas chamber A1 influid communication and the two gas chambers act as a single volume.Thus, because during movement of the piston 3 or 12 towards gas springcontrol valve 20, only the volume of gas contained within main chamber Cand first auxiliary chamber A1 are subject to compression, an evenstiffer spring curve results.

When the stiffest spring curve is desired for adjustable-volumegas-pressurized device 1, adjustment knob 67 is set by the user to thesetting at which both ball valves 50 are closed (FIG. 6D-9D). Thus,because during movement of the piston 3 or 12 towards gas spring controlvalve 20, only the volume of gas contained in the main gas chamber C issubject to compression, the stiffest spring curve results.

Applying the terminology of the '144 application as described above tothis description of an exemplary embodiment of the invention, the firstand second settings of gas spring control valve 20 may be associatedwith long travel applications and the third and fourth settings of gasspring control valve 20 may be associated with short travelapplications. Furthermore, as can be seen from Table One, the exemplarycompression ratios are smaller in long travel modes.

Additional Feature—Detent Assembly

As shown in FIG. 4B, gas spring curve control valve 20 may also includea detent assembly 196. Detent assembly 196 includes a spring 198 placedin a well 200 in rotor head 61 for biasing a ball bearing 202 intoengagement with one of a plurality of recesses (detents) 204, formed onan inner surface of second end 25 b of body portion 25 (FIG. 2C). Thespring curve of the spring 198 is selected such that the biasing forceof the spring 198 may be easily overcome so that the adjustment knob 67may be turned by hand, while also providing positive feedback as to therelative position of the rotor head 61. Preferably, the number ofdetents 204 should correspond to the number of settings for gas springcurve control valve 20. Thus, according to the first exemplaryembodiment of the invention, four (4) pairs of detents 204 may beprovided, corresponding to the four settings for gas spring curvecontrol valve 20 and a pair of ball bearings 202 (FIG. 2A).

Additional Feature—Remote Control

As described so far, adjuster adjustment knob 67 is manually anddirectly manipulated by the user at the adjustable-volumegas-pressurized device 1. However, direct and manual manipulation by theuser at the adjustable-volume gas-pressurized device 1 is not requiredto vary the setting of gas spring curve control valve 20. As shown inFIG. 11, an externally positioned remote controller 310 or electroniccontroller 330 may be positioned anywhere. For example, whenadjustable-volume gas-pressurized device 1 is associated with a bicycle,remote controller 310 or electronic controller 330 may be mounted on thehandlebars 320.

FIG. 11 is a high-level block diagram schematically depictingalternative methods for adjusting the gas spring curve control valve 20.As shown in FIG. 11, a motive source M is associated with adjustmentknob 67. Motive source M can comprise any conventional source of torque,including servo-motors and/or mechanical gear drives (neither shown).Motive source M may also be associated with a controller, for example:

(a) an electrical wire 252 for connecting motive source M to anexternally positioned electronic remote controller 310;

(b) a mechanical cable 315 for connecting motive source M to anexternally positioned mechanical remote controller 310′; and

(c) an electronic controller 330, such as a CPU, receives controlsignals from one or more sensors 331 a-c and sends control signals tomotive source M. Sensors 331 a-c may detect, such exemplary conditionsas, vertical acceleration, speed, and inclination.

Alternative Exemplary Embodiment

FIG. 12 depicts an alternative exemplary embodiment foradjustable-volume gas-pressurized device 1 and gas spring curve controlvalve 20″. Reference numerals corresponding to technical features thatremain basically unchanged from previous embodiments have been omittedfor clarity.

In this configuration, body portion 25 includes first and secondpartitions 35 a, 35 b that together define three auxiliary gas chambersA1, A2, A3, of progressively larger volumes. Three check balls (FIGS.13A-F—reference numerals omitted for clarity) interact with six camlobes and six cam grooves to provide for six different settings of gasspring curve control valve 20. Ball valves 50 (only ball valve 50 a isshown in FIG. 12) operate in the same manner as the previously describedcheck balls to control fluid communication between main gas chamber Cand auxiliary gas chambers A1, A2, A3. Note that in FIG. 12, only thegas flow port 40 between main gas chamber C and first auxiliary gaschamber A1 is shown, due to the plane of the section of FIG. 12.However, (not shown) separate gas flow ports between main chamber C andauxiliary gas chambers C1, C2, C3 are also provided and each arecontrolled by one of the ball valve as shown in FIGS. 13A-F. With thisembodiment of the invention (with design of the cam 70 as shown in FIGS.13A-13F), six different valve settings are available for selection bythe user as shown in FIGS. 13A-13F, and that result in six different gasvolumes/spring curves. However, it should be noted here that in manyapplications, such as bicycle forks, providing six or more setting maybe more than desired for typical usage. While these six settings (which,as described above may also be referred to as travel modes) aresummarized in the table below, the principles of the invention can beexpanded to any number of auxiliary chambers.

TABLE TWO Exemplary First Second Third Angular Ball Ball Ball Valve 20Position of Valve Valve Valve Effective Total Volume Setting Knob 50 5050 Occupied By Gas FIG 1 0° Closed Closed Closed C 13A 2 20° Open ClosedClosed C + A1 13B 3 40° Closed Open Closed C + A2 13C 4 60° ClosedClosed Open C + A3 13D 5 80° Open Open Closed C + A1 + A2 13E 6 100°Open Open Open C + A1 + A2 + A3 13F

It should be noted here that, although 6 discrete settings areillustrated in FIGS. 13A-13F, it is theoretically possible to design acam configuration for the exemplary embodiment of FIG. 12 that wouldprovide 2 additional discrete settings (8 total) for a device with 3auxiliary chambers as shown. Specifically, in the Table above, note thatbased on the actual cam design shown, 2 potential additionalcombinations (C+A1+A3, and C+A2+A3) are not provided for. In general, asadditional chambers are added, the total number of theoreticallypossible discrete combinations providing different total volumes rapidlyincreases. For example, for a device with a main chamber plus fourauxiliary chambers A1, A2, A3, and A4, the total number of theoreticalcombinations providing different volumes is 16. This is mentioned forcompleteness. Again, for many applications, such a large number would beundesirable and impractical for typical usage

Alternative Exemplary Embodiment

FIG. 14 represents a portion of another exemplary embodiment of theinvention. Reference numerals corresponding to technical features thatremain basically unchanged from previous embodiments have been omittedfor clarity.

In this embodiment of the invention, first end 25 a of body portion 25has a main gas flow port 350 in fluid communication with first chamber Cand ball valves 50 a, 50 b that are used to control the fluidcommunication between the main gas chamber C and the auxiliary gaschambers A1, A2.

As with prior embodiments of the invention, the opening and closing ofball valves 50 a, 50 b results from the rotation of rotor 60 (see otherFIGS) and rotor tube 62. Rotor 60 and rotor tube 62 may be rotated byany previously described method (e.g. adjustment knob 67 or motivesource M).

In this embodiment, however, rotor tube 62 has a plurality of angularlyand/or longitudinally offset detents 360 a, 360 b on its surface 361.

To open a ball valve 50, rotor 60 is rotated to align a detent 360 witha check ball 51. This alignment allows spring 52 to partially extend anddeflect check ball 51 into detent 360 and away from its valve seat/seal53. Thus, there is two-way gas flow/communication between main gaschamber C and an auxiliary gas chamber, through main gas flow port 350.In FIG. 14, ball valve 50 a is shown in the open position allowing gasflow between main gas chamber C and first auxiliary gas chamber A1 (assymbolized by the darkened lines/arrows) to allow the combined volume ofgas contained within main gas chamber C and first auxiliary gas chamberA1 to be subject to compression, thereby lowering the gas spring curveof adjustable-volume gas-pressurized device 1.

To close a ball valve 50, rotor 60 is rotated such that a detent 360will not be aligned with a check ball 51. This misalignment results incheck ball 51 abutting the surface 361 of rotor tube 62 and beingpressed radially into sealing contract with valve seal 53, which may,for example, be an o-ring. Since rotor tube 62 is fabricated from arigid material such as aluminum, spring 52 will not deflect check ball51 away from its valve seal 53. Thus, gas flow between main gas chamberC and an auxiliary gas chamber, through main gas flow port 350, isprevented. In FIG. 14, valve element 50 b is shown in the closedposition preventing gas flow between main gas chamber C and secondauxiliary gas chamber A2.

According to this embodiment, detents 360 are aligned on the surface 361of rotor tube 62 such that, as with the previous embodiments of theinvention:

1) in a first setting, both valves are open;

2) in a second setting, one of the two valves is open;

3) in a third setting, the previously open valve is closed and the othervalve is open; and

4) in a fourth setting, both valves are closed.

As with previous embodiments, more than two auxiliary gas chambers maybe provided and less than one full rotation of rotor 60 by the riderallows access to all available gas spring curves. Furthermore, as withprevious exemplary embodiments, both ball valves 50 should be open whenthe device is pressurized.

Finally, as opposed to the previous exemplary embodiments of theinvention, in this exemplary embodiment, the pressure in the main gaschamber C tends to unseat check balls 51. Also, for completeness, wenote here that this embodiment requires somewhat closer manufacturingtolerances than previous embodiments, in order to provide properoperation and sealing of the balls 51 with the seals 53. Whereas in theprevious embodiments sealing in the valve-closed position was ensured bya positive pressure in the main chamber urging the balls into sealingcontact with the seals, here proper tolerance control of the ball valvefeatures is required to ensure mechanical contact and sealing.

Alternative Exemplary Embodiment

FIGS. 15A, 15B depict a portion of another exemplary embodiment of a gasspring control valve according to the invention. This exemplaryembodiment is substantially the same as the embodiment shown, forexample, in FIG. 3, except for the area of first end 25 a of bodyportion 25. As shown in FIG. 15A, the ball valves of FIG. 3 have beenreplaced with a rotary disc valve assembly 400.

In particular, rotary disc valve assembly 400 includes a valve plate 402having multiple gas flow ports 405 angularly aligned around rotationalaxis Q-Q as described below. Valve plate 402 rotates with knob 67 (notshown in this set of FIGS) due to valve plate 402 being keyed tofastener extension 410, such as by valve plate 402 having a hexagonalshaped cut-out (not shown) that interacts with a hexagonal shapedfastener extension 410. Light spring 415 biases valve plate 402 againstseals 53. Therefore, when none of the gas flow ports 405 are alignedwith flow ports 40, 45, there is no fluid communication between mainchamber C and either of the auxiliary chambers A1, A2. However, duringpressurization (as described above), the incoming pressurized gasflowing through pressurization channel 82 flows throughout the unsealedareas around valve plate 402 and into the various chambers C, A1, A2.

The operation of this exemplary embodiment is similar to operation ofthe previous embodiment shown in FIGS. 6A-9D, for example, in that fourdifferent settings are provided. These settings are shown in FIGS. 16A-D and FIGS. 17A-D.

Using the convention with respect to FIGS. 17A-D that a filled circlerepresents a closed (blocked) gas flow port 405 that prevents gas flowand an empty circle represents an open (unblocked) gas flow port 405that allows gas flow, gas flow ports 405 are angularly aligned aboutrotational axis Q-Q such that:

1) in a first setting (FIGS. 16A, 17A), both first and second flow ports40, 45 are aligned with a gas flow port 405 and therefore, there isfluid communication between main chamber C and both of first and secondauxiliary chambers A1, A2;

2) in a second setting (FIGS. 16B, 17B), second flow port 45 is alignedwith a gas flow port 405 and therefore there is fluid communicationbetween the main chamber C and second auxiliary chamber A2. First flowport 40 is not aligned with a gas flow port 405 and therefore there isno fluid communication between main chamber C and first auxiliarychamber A1;

3) in a third setting (FIGS. 16C, 17C), first flow port 40 is alignedwith a gas flow port 405 and therefore there is fluid communicationbetween the main chamber C and first auxiliary chamber A1. Second flowport 45 is not aligned with a gas flow port 405 and therefore there isno fluid communication between main chamber C and second auxiliarychamber A2; and

4) in a fourth setting (FIGS. 16D, 17D), neither of first and secondflow ports 40, 45 are aligned with a gas flow port 405 and therefore,there is no fluid communication between main chamber C and either offirst and second auxiliary chambers A1, A2.

Note that, with this alternate embodiment, somewhat closer manufacturingtolerances are required for this portion of the structure than for theembodiment of FIG. 3, in order to provide proper sealing between valveplate 402 and both of the seals 53. Additionally, valve plate 402 ispreferably provided with a smooth, high-quality surface finish on theside contacting the seals 53. Also, each of the four gas flow ports 405through the valve plate 402 are manufactured with smooth, rounded edgesin order to prevent nicks or other damage to the seals 53 duringrotation.

CONCLUSION

While the invention has been described with respect to certain exemplaryembodiments, it is understood that many variations are apparent to oneof ordinary skill in the art from a reading of the above specificationand such variations are within the spirit and scope of the instantinvention as defined by the following appended claims.

List of Reference Numerals Used

A1, A2, A3 auxiliary gas chambers C main gas chamber M motive source Ppressure source Q axis  1 adjustable-volume gas-pressurized device  2reservoir cylinder  3 internal floating piston  10 housing  10a innerwall of housing  10′ valve housing  11 open end of housing  12 piston 13 piston shaft  20, 20′, 20″ gas spring curve control valve  21threads  25 body portion  25a, 25b first and second ends of body portion 25c body stop flats  25′ hollow tubular portion  26 seals  35, 35a, 35bpartition  40 first gas flow port  45 second gas flow port  50, 50a, 50bball valves  51, 51a, 51b check balls  52, 52a, 52b springs  53, 53a,53b seals  54 cap  55 gas flow openings  56 space  60 rotor  60a rotorslot  61 rotor head  61a rotor stop flats  62 rotor tube  63 seal  64pressurization flow path  65 exit port  67 adjustment knob  67′ lever 68 screw  69a ball bearings  69b race  69c spacer  70 cam  70a cam tab 71 screw  72 cam lobes  73 cam grooves  80 pressurization assembly  81removable cap  82 pressurization channel 196 detent assembly 198 spring200 well 202 ball bearing 204 detents 252 wire 310, 310′ remotecontroller 315 cable 320 handlebar 330 electronic controller 331a, 331b,331c sensors 350 main gas flow port 360, 360a, 360b detents 361 rotortube surface 400 rotary disc valve assembly 402 valve plate 405 flowport 410 fastener extension 415 spring

1. An adjustable-volume gas-pressurized device for a two-wheeledvehicle, comprising: a main gas chamber and at least first and secondauxiliary gas chambers; a gas spring curve control valve having aplurality of discrete settings for controlling whether differentcombinations of the main, first auxiliary and second auxiliary gaschambers are in fluid communication; and wherein the gas spring curvecontrol valve can be adjusted on-the-fly by a vehicle rider.
 2. Theadjustable-volume gas-pressurized device of claim 1, wherein the fluidcommunication between at least one of the different combinations of themain, first auxiliary and second auxiliary gas chambers comprisesunrestricted fluid communication.
 3. The adjustable-volumegas-pressurized device of claim 1, wherein the gas spring curve controlvalve includes at least one ball valve.
 4. The adjustable-volumegas-pressurized device of claim 1, wherein the gas spring curve controlvalve includes a disc valve.
 5. The adjustable-volume gas-pressurizeddevice of claim 1, associated with a bicycle suspension fork.
 6. Theadjustable-volume gas-pressurized device of claim 1, associated with abicycle shock absorber.
 7. The adjustable-volume gas-pressurized deviceof claim 6, wherein the bicycle shock absorber includes a floatingpiston.
 8. The adjustable-volume gas-pressurized device of claim 6,associated with a reservoir cylinder of a bicycle shock absorber.
 9. Anadjustable-volume gas-pressurized device, comprising: a housing, thehousing at least partially defining a main gas chamber and at leastpartially defining first and second auxiliary gas chambers; a gas springcurve control valve, at least partially within the housing, and having aplurality of discrete settings for controlling whether differentcombinations of the main, first auxiliary and second auxiliary gaschambers are in fluid communication.
 10. The adjustable-volumegas-pressurized device of claim 9, wherein the fluid communicationbetween at least one of the different combinations of the main, firstauxiliary and second auxiliary gas chambers comprises unrestricted fluidcommunication.
 11. The adjustable-volume gas-pressurized device of claim9, wherein the discrete settings at least include: a setting forpreventing fluid communication between the main gas chamber and both ofthe first and second auxiliary gas chambers; a setting for allowingfluid communication between the main gas chamber and only the firstauxiliary gas chamber; a setting for allowing fluid communicationbetween the main gas chamber and only the second auxiliary gas chamber;and a setting for allowing fluid communication between the main gaschamber and both of the first and second auxiliary gas chambers.
 12. Theadjustable-volume gas-pressurized device of claim 9, wherein the gasspring curve control valve includes: a first end; a second end; apartition intermediate the first and second ends; and the firstauxiliary gas chamber is positioned between the first end of the gasspring curve control valve and the partition; and the second auxiliarygas chamber is positioned between the second end of the gas spring curvecontrol valve and the partition.
 13. The adjustable-volumegas-pressurized device of claim 12, including: at least anotherpartition intermediate the first and second ends; and the partitions atleast partially define the first, the second, and a third auxiliary gaschambers; and the discrete settings of the gas spring curve controlvalve further includes settings for preventing or allowing fluidcommunication between the main and third auxiliary gas chambers.
 14. Theadjustable-volume gas-pressurized device of claim 11, wherein the usermay select the setting of the gas spring curve control valve using acontroller positioned externally of the gas spring.
 15. Theadjustable-volume gas-pressurized device of claim 14, wherein thecontroller positioned externally of the adjustable-volumegas-pressurized device includes a remote or electronic controller. 16.The adjustable-volume gas-pressurized device of claim 14, wherein thecontroller positioned externally of the adjustable-volumegas-pressurized device includes a knob.
 17. The adjustable-volumegas-pressurized device of claim 9, wherein the housing forms at least aportion of a suspension fork leg.
 18. The adjustable-volumegas-pressurized device of claim 9, wherein the housing forms at least aportion of a shock absorber.
 19. The adjustable-volume gas-pressurizeddevice of claim 9, wherein the housing forms at least a portion ofreservoir cylinder of a shock absorber.
 20. A gas spring curve controlvalve, comprising: (a) a body portion for at least partially defining amain gas chamber and at least two auxiliary gas chambers, the bodyportion including: (1) a first flow port allowing fluid communicationbetween the main gas chamber and the first auxiliary gas chamber; (2) asecond flow port allowing fluid communication between the main gaschamber and the second auxiliary gas chamber; (b) first and secondvalves for selectively controlling gas flow through the first and secondgas ports and having open and closed positions; (c) a rotor, the rotorassociated with the first and second valves such that rotation of therotor selectively opens or closes different combinations of the firstand second valves.
 21. The gas spring curve control valve of claim 20,wherein the fluid communication between at least one of the differentcombinations of the main, first auxiliary and second auxiliary gaschambers comprises unrestricted fluid communication.
 22. The gas springcurve control valve of claim 19, wherein at least one of the first andsecond valves includes a spring-loaded ball valve.
 23. The gas springcurve control valve of claim 22, wherein the spring biases the ballvalve towards its closed position.
 24. The gas spring curve controlvalve of claim 22, wherein the spring biases the ball valve towards itsopen position.
 25. The gas spring curve control valve of claim 20,wherein: the rotor is associated with a cam head having a plurality ofcam lobes; and rotating the rotor causes the cam lobes to open differentcombinations of ball valves.
 26. The gas spring curve control valve ofclaim 25, wherein an adjustment knob is associated with the rotor suchthat rotation of the adjustment knob rotates the rotor.
 27. The gasspring curve control valve of claim 26, wherein the adjustment knob ispositioned to allow on-the-fly manipulation.
 28. The gas spring curvecontrol valve of claim 20, wherein: the rotor further includes a surfacehaving a plurality of angularly offset detents; and rotating the rotorcauses the angularly offset detents to open different combinations ofthe ball valves.
 29. A method for selecting from among multiplepre-selected combinations of gas chambers, comprising the steps of:providing a housing including at least three gas chambers; providing agas spring curve control valve within the housing and in fluidcommunication with the at least three gas chambers; providing the gasspring curve control valve with a plurality of settings, wherein each ofthe settings selects one of multiple pre-selected combinations of the atleast three gas chambers.
 30. The method of claim 29, wherein the stepof providing a housing including at least three gas chambers includesproviding a main gas chamber and at least two auxiliary gas chambers.